Analysis of current distortion of the unsteady non-linear loads

In the paper there has been performed an assessment of the distortion of current drawn by the unsteady non-linear load, with special reference to interharmonic components. There has been studied the capability to restrain the interharmonics by means of the shunt active power filter with hysteresis control utilizing typical control algorithm based on the instantaneous power theory. As a disturbing load the 6T type thyristor bridge with RL elements of varying values in the DC circuit has been used. Studies have been performed by means of the simulation method using the network model built in the PSCAD^reg/EMTDCtrade program. The assessment of the current distortion has been performed according to the procedures defined in the EN 61000-4-7 standard.